docs: def parents(self, primary=None):
          """
          :param primary: if None, then all parents are returned. If True, then only foreign keys composed of
              primary key attributes are considered.  If False, the only foreign keys including at least one non-primary
              attribute are considered.
          :return: dict of tables referenced with self's foreign keys
          """
          return self.connection.dependencies.parents(self.full_table_name, primary)